Molly and her younger sister Jenny are at Grandpa and Grandma's, making a mud cake, fixing it with sand, adding leaves and other decorations, and baking it in the sun. But when it's time to have a bite, the girls opt for pretzels instead. Similar in concept to Sucie Stevenson's recent Do I Have to Take Violet? , this book's assets are all in the illustrations. The text is flat and pandering: ``This is going to be a very yummy cake!'' and ``Two pretzels! One for me. One for Jenny. Happy Eating!'' The lack of inspiration in the words doesn't affect the artist, but one can't help but miss the light verse of Gundersheimer's Happy Winter , which also featured two lively sisters. Ages 3-6. (Oct.)